login
A224033
Number of n X 3 0..1 arrays with antidiagonals unimodal and rows and diagonals nondecreasing.
1
4, 13, 37, 105, 298, 848, 2419, 6908, 19737, 56401, 161181, 460622, 1316360, 3761867, 10750568, 30722673, 87798365, 250907593, 717036338, 2049125344, 5855930115, 16734904820, 47824518777, 136671503209, 390575802373, 1116176041318
OFFSET
1,1
COMMENTS
Column 3 of A224038.
LINKS
FORMULA
Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - a(n-3) + 2*a(n-5).
Empirical g.f.: x*(1 - x)*(4 + x - 2*x^2 - 2*x^3) / (1 - 4*x + 3*x^2 + x^3 - 2*x^5). - Colin Barker, Aug 26 2018
EXAMPLE
Some solutions for n=3:
..0..0..1....0..0..0....0..0..0....0..0..0....0..0..0....0..1..1....0..0..0
..0..1..1....1..1..1....0..0..1....0..0..0....0..0..0....1..1..1....0..1..1
..1..1..1....0..1..1....1..1..1....0..0..1....0..1..1....1..1..1....0..1..1
CROSSREFS
Cf. A224038.
Sequence in context: A300985 A080145 A097551 * A095126 A077842 A091874
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 30 2013
STATUS
approved